Core B will provide support for all of the animal experiments in Projects 1 and 2 of the proposal. It includes oversight of quality control of ali aspects of animal purchases, maintenance of the animal colony, breeding of mice, UM Unit for Laboratory Animal Medicine regulatory communications, experimental transplantation of mice, and histopathological analysis. It is designed to enhance harmonization and efficiency of the experiments that utilize animals in Projects 1 and 2. The services provided by Core B are: 1. To oversee and monitor adherence to the standards required by the University of Michigan Unit for Laboratory Animal Medicine (ULAM) 2. To facilitate centralized and orderly animal purchases and provide for routine but uniform pretransplant and post-BMT animal care and specialized breeding ofthe knock-out mice 3. To prepare donor cell inoculums and perform BMT following irradiation in a standardized manner 4. To provide supervision for consistent scoring of clinical GVHD in the transplant models 5. To provide standardized harvesting of target organs, processing, staining (hematoxylin and eosin) and shipping of samples for histopathological analysis by Dr. Chen Liu at the University of Florida 6. To provide uniform and consistent histologic analysis of GVHD pathology in target organ tissues